1. Field of the Invention
The invention relates to the entry of control commands through portable wireless devices to remote systems.
2. Background
An embedded system is a computer. But rather than sit on a desktop, office, or research facility and run all manner of computer applications, embedded systems perform specific real-world applications like controlling complex broadcast systems, reading bar codes, printing postage stamps, or routing data over the Internet. Being so specialized, such computers may lack the usual keyboard/mouse/monitor interfaces, unless the systems they control are very complex, in which case, such an interface is used to provide “soft-key” controls and readouts for the many parameters of interest.
The desire to provide remote access to such systems, to allow them to be “unmanned,” has been recognized for some time and several solutions are known. Remote access is attractive because it allows the systems to be monitored and controlled from a geographical location outside the facility where the equipment is installed and otherwise controlled. Remote access is most desirable when such equipment is inaccessible due to terrain, convenience, or as a result of an unpredicted lack of personnel such as due to absenteeism or a crisis. (There is a story of a broadcast system that was suddenly abandoned, due to a gunman, while it was still broadcasting live creating a sudden need for remote control to keep the broadcast on-line.) Also, as a matter of convenience and economy, the monitoring of mission-critical equipment by “on-call” personnel is considerably more practical when supervisors do not have to be physically present at the facility. Fault isolation by field service personnel may be more timely and efficient when electronic service calls can be substituted for a personal visit. Emergency access is a key concern of remote access. In emergency situations, a facility may need to be evacuated even while its equipment needs direction to function without interruption. Examples of these mission-critical facilities are broadcast studios with air-time commitments, manufacturers of sensitive or dangerous chemicals or components, security intensive installations, and Internet service providers.
Current methods of providing remote access to commercial or industrial embedded systems involve a variety of techniques. A common approach is via a dial-up connection through a modem over standard phone lines. For critical equipment, a phone line may be leased to provide a dedicated, guaranteed connection, or to provide access for continuous monitoring. Once a connection is established with the remote equipment, using either kind of connection, communication is usually conducted using a serial protocol the equipment is designed to understand and respond to.
A more modern mechanism for interfacing with embedded systems is through remote access via a local access network (LAN), wide area network (WAN), or the Internet. This may utilize Internet protocols for control, and status. Information is transferred between the remote control/monitoring station and the embedded system by packets, for example using the Internet protocol (IP). Another packet protocol that has gained favor for such systems is simple network management protocol (SNMP) has gained wide favor for monitoring and controlling the collections of devices that comprise a network infrastructure.
The growth of Internet technologies has enabled a remarkably successful method of remote access using the HTTP protocol and a Web browser. HTTP, is a protocol that runs on top of IP and is used for the world wide web (WWW). To access HTTP enable devices, a user need only supply the uniform resource locator or URL (or IP address) to a Web browser. The embedded system acts like a web server and returns a web page with information, controls (like check boxes, text boxes, and radio buttons), text data providing status, graphs, etc. just like a web page. The Web page from the embedded system device may be written in Hyper Text Markup Language (HTML), the basic language used for familiar web pages. It may display the current status of the equipment and provide graphical forms to allow a user to update control values. When the user submits a completed form, a URL is returned to the equipment with parameters reflecting the updated parameter values embedded in a request string. The embedded equipment then acts on the request through a Common Gateway Interface (CGI) or with a Request Processing Module (RPM). Once the control request is processed, the updated state of the equipment is returned to the user's Web browser as another Web page. Thusly, content is supplied dynamically from the embedded system. The content may be, for example, a snapshot of the state of the device when the HTML response was generated. Put simply, the embedded system is controlled by sending data to the embedded system in the same way a web page form sends data to a web server. Instead of simply updating information in a database at the server, the embedded system makes the data sent to it available to the control system which then causes the embedded system to change its settings.
While most remote access methods require the operator to be wired to the equipment, some forms of access, especially emergency system access, may be better served by a wireless connection. Wireless control methods are available, but are limited due to the complexity of a two-way radio link, and the size limitations of typical mobile control devices. The simplest of these mobile control devices utilize a cell phone with recorded or synthesized voice status and dial-tone push button (dual-tone multi-frequency or DTMF) control. Anyone who has navigated a voice-mail system with a touch-tone phone is familiar with the shortcomings of wireless phones as control devices. Wireless local networks are available, but are by their nature an extension of the facility's control network, and not intended for use very far from the confines of the equipment room.
For the purposes of this invention, technology now exists to extend the World Wide Web to wireless devices. But, this technology has not yet been employed for the control of commercial or industrial embedded systems. Current wireless remote access techniques lack the features enjoyed by wired access. Specifically, wireless control devices tend to be custom-built and limited in operating range from the facilities to which they have access. The control interfaces of these devices are also limited in terms of how easily they may be upgraded and expanded in terms of functionality. Solutions that use a widely accepted control paradigm that is inherently flexible may also require training to operate. Also, the wireless control device cannot be used for other applications. Above all, the cost of such systems is usually prohibitive since these devices do not approach the mass-market volumes required for favorable pricing. Consequently, the most widely used wireless remote access solution involves calling another operator at the facility with a cell phone. This does not satisfactorily address situations where access is impossible due to geographic or weather isolation, and especially crisis situations where the facility must be evacuated.